In chemical and biochemical operations such as solvent extraction, steam distillation and azeotropic distillation, immiscible liquids must often be funneled and separated from each other. In liquid--liquid extractions, liquids may be contacted by agitation, followed by a settling period, followed by removal of one or more layers of liquid. Separatory funnels are usually used to make these separations. The separation of immiscible liquids, usually an organic soluble liquid and an aqueous soluble liquid, using a separatory funnel, is a well-known procedure.
Separatory or pouring funnels are conventional. Examples of such funnels can be found in U.S. Pat. No. 1,662,147 issued to Nels Farden on Mar. 13, 1928 and European Patent Specification EP-B1 198 710 published on Jun. 30, 1989. U.S. Pat. No. 1,662,147 describes a funnel of basically conventional shape to which have been longitudinally attached inwardly extending flanges which prevent the whirling tendency of liquid poured into the funnel. European Patent Specification EP-B1 198 710 describes a pouring funnel with one or more radially extending baffle members. The baffles are hollow, and formed as re-entrant portions of the wall of the funnel, so that their interior surfaces are open to the outside. This allows air to be vented from the funnel and prevents swirling of the liquid when poured through the funnel. In the above patent and publication, the outlet opening is completely unobstructed, never covered by the baffle or flanges.
A common problem with funnels used in funneling or dispensing liquids is that when a liquid is poured into the funnel and allowed to run out the funnel through its relatively small outlet opening, a whirling or circular motion is set up and may be carried to such an extent that a cavity will be formed through the body of the liquid. If the liquid is a mixture of immiscible liquids that have been allowed to separate into layers, this vortex can cause the layers to again mix, necessitating the need for additional separations or back extraction. During the operations of funneling, separating and dispensing, vortexing causes the liquid to flow through the funnel much more slowly than it would if the entire exit opening were constantly filled with liquid. Thus, a need exists to provide a funnel which will prevent the above described vortexing action of the liquid passing therethrough, thereby reducing the amount of time necessary for funneling, separating, or dispensing liquids.
Layers of immiscible liquids lend themselves to separation so long as there is enough distinction between them that their interface is discernible. However, it is often the case that the interface between two layers is virtually indistinguishable, especially with dark liquids. Thus, during separation a portion of the lower layer may be left in the funnel, or the upper layer may become mixed with the lower layer - both necessitating back extraction.